import yfinance as yf


def stock_exists(ticker):
    try:
        yf.Ticker(ticker).info
        return True
    except KeyError:
        return False

def get_current_price(ticker):
    yf_obj = yf.Ticker(ticker)
    todays_data = yf_obj.history(period='1d')
    return round(todays_data['Close'][0], 2)

def get_delta(ticker, return_old_price=False):
    yf_obj = yf.Ticker(ticker)
    old_price = yf_obj.history(interval='1d')['Close'][-2]
    current_price = get_current_price(ticker)
    delta = 100 * ( (current_price / old_price) - 1 )
    if return_old_price:
        return delta, old_price
    else:
        return delta

def get_delta_old_price(ticker):
    yf_obj = yf.Ticker(ticker)
    return yf_obj.history(interval='1d')['Close'][-2]